USGS Hill Shade (or Shaded Relief) is a tile cache base map created from the National Elevation Dataset (NED), a seamless dataset of best available raster elevation data for the conterminous United States, Alaska, Hawaii, and Territorial Islands. Derived from the NED using a hill shade technique, this base map represents a continental view showing shaded relief from USGS NED layers at resolutions of 1/3-, 1-, and 2-arc-second (in Alaska only). Shaded relief (or hill shade) function parameters are: point illumination is from the NW (azimuth = 315 degrees), and altitude of the light source is 45 degrees. Color characteristics are the result of applying a color ramp in which RGB values range from white (RGB: 255, 255, 255) to brown (RGB: 166, 150, 109). The color ramp was applied with a Stretch Type of None. Contrast and Brightness values range from 4-14%, depending on scale, for cartographic purposes. For additional information on NED, go to http://ned.usgs.gov.